`cargo build --no-default-features --features=unstable` fails

[Keruspe]

error[E0433]: failed to resolve: unresolved import
  --> src/utils.rs:70:42
   |
70 |     once_cell::sync::Lazy::force(&crate::rt::RUNTIME);
   |                                          ^^
   |                                          |
   |                                          unresolved import
   |                                          help: a similar path exists: `std::rt`